1. Field of the Invention
The present invention relates to a composite layer which can be used in the preparation of colored glass material for ornamental purposes, in the preparation of composites applicable as construction materials including walling, flooring, and kitchen counter materials, etc. (in particular, materials commercially marketed under the names artificial marble, artificial granite, etc.), as well in the preparation of products such as color filters, etc., and a method of manufacturing the same.
The present invention particularly relates to color filter which can be employed for purposes such as color compensation in VTR cameras, color separation used in colored copying machines such as input colored scanners, etc., RGB color separation in liquid crystal color matrices, general photographic applications, special purposes such as UV cutoff, etc., and to a method of manufacturing the same.
2. Description of the Prior Art
The coloring of glass arises from a nonuniformity in the degree to which light of the various wave lengths contained in the visible spectrum is transmitted when visible light passes through the glass. Utilizing this property, four principal methods of manufacturing colored glass have hitherto been developed and used, as follows.
(a) Ions of transition metals or rare earth elements are confined within the glass, and the light of prescribed wave lengths is absorbed by electron transitions in these metal ions.
(b) Minute particles of chemical elements or compounds are dispersed within the glass in colloidal form, and light is scattered and/or absorbed by these colloids.
(c) Light is absorbed by color centers created by exposing the glass to radiation, etc.
(d) Color is imparted by coating the surface of the glass with coating materials containing organic dyes, pigments, etc., or by vapor deposition of a metallic film.
Metal ions such as titanium, vanadium, or chromium, etc., are used as a colorant in the aforesaid method (a). When this method is employed, the colors change in a complex manner owing to the changes in coordination numbers of the metal ions which are determined by the specific composition of the glass.
In method (b), coloration is effected through colloid precipitation induced by heat treatment. Copper and gold are used to create red colors, while silver is used for yellow coloration.
Method (c) is used for the creation of certain special colors.
Method (d) is the so-called coating method, and involves no coloration arising from the composition of the glass itself.
The formation of composite materials consisting of glass and synthetic resins from compositions containing, e.g., glass particles, reaction hardened synthetic resins, and flaky aluminum powder, has previously been proposed (Japanese Laid-Open Patent Publication No. 55-20222); construction materials such as artificial marble, etc., can be formed from such compositions. Hitherto, there have existed three main types of composition used in composites for the fabrication of artificial marble and artificial granite, as follows;
The first type comprises a composite material of crushed natural rock particles and synthetic resins.
The second type comprises a composite material of glass powder and synthetic resins, as indicated in the above-cited announcement (Japanese Laid-Open Patent Publication No. 55-20222).
The third type comprises a composite material of aluminum hydroxide powder end synthetic resins.
The methods which have been employed for the coloration of these composite materials consist of the use of naturally colored rock, or of glass particles colored with organic pigments, or of glass colored with metallic ions.
The range of colors which can be obtained by conventional methods of coloring glass with metallic ions or metallic colloids is limited. That is, the arbitrary control of the wave length peak of the light absorbed or transmitted by the glass is difficult. Moreover, colored glass fabricated by the aforementioned costing method, based upon application of coating materials containing dyes or pigments, is subject to fading when exposed to ultraviolet radiation, heat, or moisture, etc.
As regards the fabrication of artificial marble, the appearance of composite materials employing natural rock as a colorant conveys no impression of transparency or depth of color, moreover, the color of such materials changes concomitantly with temporal changes in the ferric oxide which constitutes the colored component of the rock; furthermore, since the said colorant is of natural origin, accurate reproduction of colors is difficult. On the other hand, composite materials employing colored glass do convey an impression of transparency and are suited for mass production. However, in the case of composite materials prepared with finely powdered glass, since the glass powder is colored with organic pigments, the weather resistance of the product with respect to ultraviolet radiation is poor. As for composite materials prepared with crushed glass colored with metallic ions or colloids, the range of color selection for such composite materials is limited. Lastly, since composite materials prepared with aluminum hydroxide powder are generally colored with organic pigments, such composite materials are subject to considerable fading.
Next, the use, as color filters, of a composite layer comprising a transparent substrate and a colored layer superposed upon this substrate will be explained below.
Color filters are classified in accordance with their uses, as follows;
(1) Color correction filters in VTR cameras, facsimile machines, illumination meters, etc. PA1 (2) Color separation filters in liquid crystal displays, CRT displays, etc. PA1 (3) Contrast correction, color temperature conversion and neutral density filters in general photographic applications. PA1 (4) Special purpose filters for ultraviolet cutoff, etc. PA1 (5) Color filters for traffic lights and window glass. PA1 (1) Organic film filters, formed by dispersing a coloring dye or pigment in an organic resin film, such as a polyethylene film, etc. PA1 (2) Filters formed on a glass substrate by printing or electrodepositing and drying a mixture of gelatin or an organic resin binder, such as a polyester resin, and a coloring dye or pigment. PA1 (3) Glass filters colored by ions of transition metals such as Cuo or La.sub.2 O.sub.3 or rare earths, or precipitation of colloidal metals such as Au, or CdS, or colloidal compounds. PA1 (4) Vapor deposited metal filters, utilizing the light transmission characteristics of vapor deposited metals films. PA1 (1) Providing a composite layer so that no fading results from exposure to ultraviolet radiation, heat, or moisture (i.e., possessing excellent weather resistance); PA1 (2) Providing a composite layer permitting an extremely great freedom of selection of the wave length peak of transmitted light when organic dyes or organic pigments are used for coloration; PA1 (3) Providing a composite layer which can be fabricated with comparative ease; PA1 (4) Providing color filters possessing the various aforesaid characteristics; PA1 (5) Providing glass composite materials comprising the various aforesaid characteristics; and PA1 (6) Providing glass composite materials characterized by strong adhesion between the composite layers and synthetic resin layers.
For example, with the color correction filters for a VTR camera, color corrections thereof are necessary due to the large difference between human visibility and the sensitivity of a photoelectric conversion element (solid image pick-up element).
For example, color correction filters appropriate for the brightness of the scene and the color of the light source are necessary for photography. The types of filters used for color correction in recent years comprise near infrared cutoff filters, ultraviolet cutoff filters, and three color filters, i.e., red (R), green (G), and blue (B).
FIGS. 10, 11, and 12 illustrate cross-sections of representative light receptors of conventional color sensors. The color sensor light receptor illustrated shown in FIG. 10 comprises a photomask IC 20 with spacers 19 arranged on its surface, and a film filter 21 located above the photomask IC 20, with a red (R), a green (G), a blue (B) filter strayed in a plane on the surface of the film filter for the purpose of color separation, above which are situated an ultraviolet cutoff filter 22 and a near infrared cutoff filter 23. Translucent glass or a vapor deposition film is used as the near infrared cutoff filter 23, while translucent glass or an organic film is used as the ultraviolet cutoff filter 22. The sensor light receptor illustrated in FIG. 11 has, in place of the film filter 21 shown in FIG. 10, a printed filter 25. On this printed filter 25, red, green, and blue colored layers 21 are formed by the printing of dyes on the surface of the translucent glass substrate 24 opposing the photomask IC 20. The light sensor receptor illustrated in FIG. 12 employs, in place of the film filter shown in FIG. 10 or the printed filter 25 shown in FIG. 11, a glass filter 26 comprising red, green, and blue colored glass filter elements. The colored elements of this glass filter 26 do not fade upon exposure to ultraviolet rays, and therefore the above-mentioned ultraviolet cutoff filter 22 is not required in this case.
Conventional color filters may be classified as follows;
The various problems associated with conventional color filters are as follows;
Organic film filters, printed filters, electrodeposited filters, etc., all employ organic substances as binders for dyes or pigments. Consequently, such filters are prone to fading upon exposure to ultraviolet rays. If dyes are used as a colorant, since the binder possesses no ultraviolet cutoff effect, then the dyes themselves are substantially faded by ultraviolet rays, and as a result the peak absorption wave length of the filter changes with the passage of time. In order to prevent this, the filter is covered with a substance such as crystal or quartz which can absorb ultraviolet radiation, or is placed in a vacuum to ensure long-term reliability, etc.
On the other hand, in glass filters, since the glass itself is colored by metal or metal ions contained in the glass, almost no fading results from exposure to ultraviolet radiation, however, as illustrated in FIG. 12, the glass filter requires a holder 28. Moreover, arbitrary control of the peak transmission wave length is more difficult compared with filters employing organic dyes or pigments. The fabrication of vapor deposited filters demands a great deal of time and labor, moreover, the range of absorption wave lengths and other optical characteristics of such filters is limited.